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Effects of carbohydrate supplementation on muscle glycogen and substrate oxidation during extended exercise in females

Year: 2005
Type: dissertation
Study design: Clinical Trial
Abstract: To determine the effects o f CHO feeding during 10-hours o f moderate exercise on muscle glycogen and substrate utilization in females.METHODS: Six moderately trained females (age 23±3 yr, eumenorrheic and not taking oral contraceptives) completed a double blind, random crossover design protocol.Subjects ingesting either a CHO (0.6g CHO/kg fat free mass (FFM) of a 20% maltodextrin solution) or placebo (PLA) drink each hour for 10 hours of exercise.Each hour included 9 minutes on an arm ergometer, 19 minutes on a cycle ergometer (CE) and 20 minutes on a treadmill (TM), each at 70% of mode specific ventilatory threshold (VT) with 10minute rest and feeding.A standardized lunch was provided (5.5 g/kg FFM CHO, and 1.3 g/kg FFM protein) during both trials after the fifth hour.Muscle biopsies were obtained pre-and post-exercise from the vastus lateralis, and metabolic gases were collected every other hour on the TM.Blood glucose was continuously measured with an indwelling glucose sensor, and total urine void was collected.RESULTS: Whole body CHO oxidation was significantly higher during the CHO trial (269.1±64.1g)compared to PLA (209.6±45.8g,p<0.01).Rates of muscle glycogenolysis were about 50% lower during the CHO trial (2.5±1.8 vs. 5.4±2.2mmol/kg wet wt./hr, p<0.05).Blood glucose was not different across trials.Total urinary nitrogen was also similar for both trials (525.2 ± 455.3 and 617.7 ± 508.2 mg/dl, for CHO and PLA respectively, p>0.05).CONCLUSION: These data indicate that regular CHO feedings maintain whole body CHO oxidation and markedly reduces muscle glycogenolysis during 10 hours o f moderate intensity intermittent exercise in females.
Language: English
Field: Nursing
Open Access status: green
OpenAlex ID: W1444728228
Cites: 32
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Related to: 10